1 Field of the Invention
The present invention relates to a technique for performing printing by forming dots on a printing medium while carrying out a main scan, and more particularly to a technique for performing printing, which contains a dot recording area, a blank area and a dot recording area in the sub-scan direction on the printing paper.
2. Description of the Related Art
In recent years, the type of printer, which ejects ink from a print head, has come into widespread use as an output device for computers. Among such printers, there are those that print images by forming dots on a printing medium by ejecting drops of ink from nozzles while executing a main scan. And printers such as this print images on printing paper by executing sub-scans between main scans.
In this type of printer, the following technique is known as a technique used to print images in which dot recording area, blank area and dot recording area are aligned in the sub-scanning direction. In this technique, dots are recorded in a single main scan on as many lines as there are nozzles which are aligned in the sub-scanning direction on a printing head. Then, sub-scanning is carried out only to the extent of the width of the areas in which recording of the dots has been completed. Another main scan is carried out and dots are recorded on as many lines as there are nozzles. Then, the dots continue being recorded one after another in a width area corresponding to the number of nozzles on the printing paper. The bundle of lines which can be recorded in a single main scan will be referred to hereafter as xe2x80x9crecording bandxe2x80x9d. When there are no dots to be recorded on the recording band scheduled to be recorded next, this printer records the dots on the recording band scheduled to be recorded after that, without a main scan on the recording band scheduled to be recorded next.
When this printer is used, the amount of feed for the sub-scan is usually the width of the recording band. When there are no dots to be recorded in a specific area on the printing paper, sub-scan feeding equivalent to n times (n is an integer of 1 or greater) the width of the recording band is carried out up to the position of the recording band which includes the dots to be recorded and the dots are then recorded.
The amount of sub-scan feed in the printer mentioned above is limited to the feed amount equivalent to n times (n is an integer of 1 or greater) the width of the recording band. Therefore, in printing images, in which the dot recording area, the blank area and the dot recording area are aligned in the sub-scan direction, the sub-scanning could not be carried out efficiently.
The present invention was designed to solve for the above-mentioned problems of the prior art. An object [of the present invention] is to efficiently perform printing, in which a dot recording area, a blank area and a dot recording area are lined up in the sub-scan direction on the printing paper.
To solve at the least a portion of the above-mentioned problems, the present invention carries out predetermined processing intended for a printing apparatus, which performs printing by forming dots by ejecting drops of ink from nozzles and depositing same on a printing medium. This printing apparatus comprises a print head which has a nozzle group comprising N (where N is an integer of 2 or greater) nozzles for ejecting drops of ink which are arrayed at a nozzle pitch D which is equivalent to the main scan line pitch D; a main scan driving unit for performing a main scan which moves at least one of the print head and the printing medium; a sub-scan driving unit for performing a sub-scan which moves at least one of the print head and the printing medium in a sub-scan direction that intersects with a direction of the main scan; and a control unit for controlling the print head, the main scan driving unit and the sub-scan driving unit.
With such printing apparatus, the printing is performed such that a first dot recording area in which dots are to be formed, a blank area in which dots are not formed, and a second dot recording area in which dots are to be formed exist in order on the printing medium in the sub-scan direction. A unit scan operation which comprises a single main scan is performed for forming dots on main scan lines of the first dot recording area, while executing an inter-band sub-scan according to a predetermined feed amount SSb between the respective unit scan operations. After completing the forming of dots in the first dot recording area, a positioning sub-scan feed is carried out for executing a sub-scan to obtain a relative position at which a position of an upper end nozzle of the N nozzles coincides with a position of an upper end main scan line of the second dot recording area in the sub-scan direction. Using such a mode makes it possible to shorten the time required for printing, and to perform printing efficiently.
It is preferable that the positioning sub-scan feed is executed only when a specific main scan line is included in the blank area and a number of main scan lines Lr is N or more. The specific main scan line is positioned below and adjacent to a main scan line where a lower end nozzle of nozzles used in the unit scan operation is positioned when an unit scan operation executed immediately before the positioning sub-scan has ended. The Lr is a number of main scan lines counted from the specific main scan line to a main scan line at a lower end of the blank area. Using such a mode makes in possible to reduce the number of sub-scans when printing on a printing medium.
A feed amount of the positioning sub-scan feed may be (SSb+Lr)xc3x97D. Further, Lr can also be a value other than the value of an integral multiple of N. That is, when n is an integer of 0 or greater, and xcex1 is a positive integer of less than N, Lr can take a value that satisfies the equation Lr=nxc3x97N+xcex1.
Furthermore, when printing is performed using a plurality of nozzle groups, each comprising a plurality of nozzles, each of which is a nozzle for ejecting drops of ink, and these nozzles are arrayed at a nozzle pitch D that is equivalent to the main scan line pitch D, it is also possible to perform printing such as the following. The plurality of nozzle groups includes a lower end nozzle group is a nozzle group whose upper end nozzle is positioned at a lowermost place among upper end nozzles of the plurality of nozzle groups. A positioning sub-scan feed may be carried out for executing a sub-scan to obtain a relative position at which a position of an upper end nozzle of the lower end nozzle group coincides with a position of an upper end main scan line of the second dot recording area in the sub-scan direction. Using a mode such as this, whether the nozzle group is disposed in a location so as to be lined up in the direction of the main scan, and whether the nozzle group is disposed in a different location in a sub-scan direction that intersects with a direction of the main scan, it is possible to record dots without gaps from the upper end of the second dot recording area.
The feed amount of the positioning sub-scan feed may be decided as follows. (i) A parameter i is set at one. (ii) It is determined whether or not an aggregate of main scan lines contains a pixel to be recorded with an ink dot. The aggregate of main scan lines are lines that are to be printed by the nozzle groups when it is assumed that a sub-scan of feed amount of (SSbxc3x97i) and the unit scan operation are to be executed. (iii) The parameter i is incremented by one. The operations (ii) and (iii) are repeated until the aggregate of main scan lines containing a pixel to be recorded is found.
Then a number of inner-band blank lines is counted. The inner-band blank lines are lines in the aggregate of main scan lines to be decided to contain a pixel to be recorded a dot, and are consecutive main scan lines that do not contain a pixel to be recorded with an ink dot and are lined up without gaps in the sub-scan direction from a top of the aggregate of main scan lines. The positioning sub-scan feed of feed amount {SSbxc3x97(i0xe2x88x921)+j0} is executed. The xe2x80x9ci0xe2x80x9d is the i when the aggregate of main scan lines containing a pixel to be recorded is found and the xe2x80x9cj0xe2x80x9d is a number of the inner-band blank lines. With such a mode, the feed amount of the positioning sub-scan feed can be decided by studying the pixels in the unit of the aggregation of main scan lines that may be recorded dot in one unit scan operation.
The nozzle groups may be positioned such that they do not overlap one another in a direction perpendicular to the direction of the main scan, and may comprise p (where p is an integer of 2 or greater) nozzle groups for ejecting drops of ink of mutually different colors. Since using such a mode establishes the sequence by which drops of ink of each color are deposited on printing paper during printing, printing results are of high quality.
The p nozzle groups each may comprise N (where N is an integer of 2 or greater) nozzles. The nozzles included in each of the p nozzle groups may be arranged at a fixed nozzle pitch D in the direction perpendicular to the direction of the main scan. In such an embodiment, it is preferable that the positioning sub-scan feed is only executed when a width of the blank area in the direction perpendicular to the direction of the main scan is greater than {Nxc3x97(pxe2x88x921)}xc3x97D. Using a mode such as this enables the feed amount of a positioning sub-scan feed to be made longer that the feed amount of an inter-band sub-scan.
A feed amount of a positioning sub-scan feed may be {Lrtxe2x88x92Nxc3x97(pxe2x88x922)}xc3x97D. The Lrt represents a number of main scan lines counted as follows. The p nozzle groups include an upper end nozzle group including an uppermost nozzle of nozzles used in the unit scan operation. It is counted from a main scan line immediately below to a main scan line where a lower end nozzle of the upper end nozzle group is positioned in a state where a unit scan operation executed immediately before the positioning feed has ended. The number Lrt is counted to a main scan line of a lower end of the blank area. Using a mode such as this makes it possible to record dots without gaps from the upper end of the second dot recording area.
Further, efficient printing can also be performed by carrying out prescribed processing in a printing apparatus such as that hereinbelow. The printing apparatus has a print head which has a nozzle group comprising N (where N is an integer of 2 or greater) nozzles for ejecting drops of ink which are arrayed at a nozzle pitch kxc3x97D that is k times (where k is an integer of 2 or greater) a main scan line pitch D.
A unit scan operation is preferably performed for forming dots on main scan lines of the first dot recording area. The unit scan operation comprises k main scans and (kxe2x88x921) sub-scans executed between the respective main scans by a predetermined first feed amount SSm, while executing inter-band sub-scans by a predetermined second feed amount SSb between unit scan operations. Then after completing the forming of dots in the first dot recording area, a positioning sub-scan feed may preferably be carried out for executing a sub-scan to obtain a relative position where an upper end main scan line of a unit band coincides with a main scan line of an upper end of the second dot recording area. The unit band is a bundle of consecutive main scan lines lined up without gaps in the sub-scan direction that are to be printed by the nozzle group when it is assumed that the unit scan operation is executed once after the positioning sub-scan feed. Using a mode such as this makes it possible to shorten the time required for printing and to perform printing efficiently, when performing printing such that the main scan line pitch is a fraction of the nozzle pitch.
It is preferable that the positioning sub-scan feed is executed only when a specific main scan line is included in the blank area and a number of main scan lines Lr is Nxc3x97k or more. The specific main scan line is positioned below and adjacent to a main scan line where a lower end nozzle of nozzles used in the unit scan operation is positioned when an unit scan operation executed immediately before the positioning sub-scan has ended. The Lr is a number of main scan lines counted from the specific main scan line to a main scan line at a lower end of the blank area. Using a mode such as this makes it possible to reduce the number of sub-scans when printing on a printing medium.
A feed amount of the positioning sub-scan feed is preferably be (SSb+Lr)xc3x97D. Further, Lr can also be a value other than the value of an integral multiple of SSb. That is, when n is an integer of 0 or greater, and xcex12 is a positive integer of less than SSb, Lr can take a value that satisfies the equation Lr=nxc3x97SSb+xcex12.
The print head may have a plurality of nozzle groups each comprising a plurality of nozzles for ejecting drops of ink which are arrayed at a nozzle pitch kxc3x97D that is k times (where k is an integer of 2 or greater) a main scan line pitch D. The plurality of nozzle groups includes a lower end nozzle group whose upper end nozzle is positioned at a lowermost place among upper end nozzles of the plurality of nozzle groups. Using a mode such as this can also make it possible to shorten the time required for printing and to perform printing efficiently, when performing printing such that the main scan line pitch is a fraction of the nozzle pitch.
The feed amount of the positioning sub-scan feed may be decided as follows. (i) A parameter i is set at one. (ii) It is determined whether or not an aggregate of main scan lines contains a pixel to be recorded with an ink dot. The aggregate of main scan lines are lines that are to be printed by the nozzle groups when it is assumed that a sub-scan of feed amount of {SSbxc3x97i+SSmxc3x97(kxe2x88x921)xc3x97(ixe2x88x921)} and the unit scan operation are to be executed. (iii) The parameter i is incremented by one. The operations (ii) and (iii) are repeated until the aggregate of main scan lines containing a pixel to be recorded is found.
Then a number of inner-band blank lines is counted. The inner-band blank lines are lines in the aggregate of main scan lines to be decided to contain a pixel to be recorded a dot, and are consecutive main scan lines that do not contain a pixel to be recorded with an ink dot and are lined up without gaps in the sub-scan direction from a top of the aggregate of main scan lines. The positioning sub-scan feed of feed amount {SSb+SSmxc3x97(kxe2x88x921)}xc3x97(i0xe2x88x921)+j0 is executed. The xe2x80x9ci0xe2x80x9d is the i when the aggregate of main scan lines containing a pixel to be recorded is found and the xe2x80x9cj0xe2x80x9d is a number of the inner-band blank lines. With such a mode, the feed amount of the positioning sub-scan feed can be decided by studying the pixels in the unit of the aggregation of main scan lines that may be recorded dot in one unit scan operation.
The nozzle groups may be positioned such that they do not overlap one another in a direction perpendicular to the direction of the main scan, and comprise p (where p is an integer of 2 or greater) nozzle groups for ejecting drops of ink of mutually different colors.
The p nozzle groups each may comprise N (where N is an integer of 2 or greater) nozzles, and the nozzles included in each of the p nozzle groups may be arranged at a fixed nozzle pitch kxc3x97D in the direction perpendicular to the direction of the main scan. In such a case, it is preferable that the positioning sub-scan feed is only executed when a width of the blank area in the direction perpendicular to the direction of the main scan is greater than {Nxc3x97kxc3x97(pxe2x88x921)}xc3x97D. Using a mode such as this enables the feed amount of a positioning sub-scan feed to be made longer than the feed amount of an inter-band sub-scan, when performing printing such that the main scan line pitch is a fraction of the nozzle pitch.
In above embodiment, a feed amount of a positioning sub-scan feed is preferably be {Lrtxe2x88x92Nxc3x97kxc3x97(pxe2x88x922)}xc3x97D. Using a mode such as this makes it possible to record dots without gaps from the upper end of the second dot recording area, when performing printing such that the main scan line pitch is a fraction of the nozzle pitch.
Furthermore, the present invention can be achieved using a variety of modes, such as those shown hereinbelow.
(1) Printing method, printing control method
(2) Printing apparatus, printing control apparatus
(3) A computer program for realizing the above-mentioned devices and methods.
(4) A recording medium on which is recorded a computer program for realizing the above-mentioned devices and methods.
(5) Data signals, which comprise a computer program for realizing the above-mentioned devices and methods, and which are embodied inside a carrier wave.